1 /*
2  * Copyright (c) 2018 Stefan Sperling <stsp@openbsd.org>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include <sys/types.h>
18 #include <sys/queue.h>
19 
20 #include <sha1.h>
21 #include <stdio.h>
22 #include <stdlib.h>
23 #include <string.h>
24 #include <util.h>
25 #include <zlib.h>
26 
27 #include "got_error.h"
28 #include "got_object.h"
29 #include "got_repository.h"
30 #include "got_reference.h"
31 
32 #include "got_lib_sha1.h"
33 #include "got_lib_path.h"
34 #include "got_lib_delta.h"
35 #include "got_lib_zbuf.h"
36 #include "got_lib_object.h"
37 
38 /* A symbolic reference. */
39 struct got_symref {
40 	char *name;
41 	char *ref;
42 };
43 
44 /* A non-symbolic reference (there is no better designation). */
45 struct got_ref {
46 	char *name;
47 	u_int8_t sha1[SHA1_DIGEST_LENGTH];
48 };
49 
50 /* A reference which points to an arbitrary object. */
51 struct got_reference {
52 	unsigned int flags;
53 #define GOT_REF_IS_SYMBOLIC	0x01
54 
55 	union {
56 		struct got_ref ref;
57 		struct got_symref symref;
58 	} ref;
59 };
60 
61 static const struct got_error *
62 parse_symref(struct got_reference **ref, const char *name, const char *line)
63 {
64 	struct got_symref *symref;
65 	char *symref_name;
66 	char *symref_ref;
67 
68 	if (line[0] == '\0')
69 		return got_error(GOT_ERR_NOT_REF);
70 
71 	symref_name = strdup(name);
72 	if (symref_name == NULL)
73 		return got_error_from_errno();
74 	symref_ref = strdup(line);
75 	if (symref_ref == NULL) {
76 		const struct got_error *err = got_error_from_errno();
77 		free(symref_name);
78 		return err;
79 	}
80 
81 	*ref = calloc(1, sizeof(**ref));
82 	if (*ref == NULL)
83 		return got_error_from_errno();
84 	(*ref)->flags |= GOT_REF_IS_SYMBOLIC;
85 	symref = &((*ref)->ref.symref);
86 	symref->name = symref_name;
87 	symref->ref = symref_ref;
88 	return NULL;
89 }
90 
91 static const struct got_error *
92 parse_ref_line(struct got_reference **ref, const char *name, const char *line)
93 {
94 	uint8_t digest[SHA1_DIGEST_LENGTH];
95 	char *ref_name;
96 
97 	if (strncmp(line, "ref: ", 5) == 0) {
98 		line += 5;
99 		return parse_symref(ref, name, line);
100 	}
101 
102 	ref_name = strdup(name);
103 	if (ref_name == NULL)
104 		return got_error_from_errno();
105 
106 	if (!got_parse_sha1_digest(digest, line))
107 		return got_error(GOT_ERR_NOT_REF);
108 
109 	*ref = calloc(1, sizeof(**ref));
110 	if (*ref == NULL)
111 		return got_error_from_errno();
112 	(*ref)->ref.ref.name = ref_name;
113 	memcpy(&(*ref)->ref.ref.sha1, digest, SHA1_DIGEST_LENGTH);
114 	return NULL;
115 }
116 
117 static const struct got_error *
118 parse_ref_file(struct got_reference **ref, const char *name,
119     const char *abspath)
120 {
121 	const struct got_error *err = NULL;
122 	FILE *f = fopen(abspath, "rb");
123 	char *line;
124 	size_t len;
125 	const char delim[3] = {'\0', '\0', '\0'};
126 
127 	if (f == NULL)
128 		return got_error(GOT_ERR_NOT_REF);
129 
130 	line = fparseln(f, &len, NULL, delim, 0);
131 	if (line == NULL) {
132 		err = got_error(GOT_ERR_NOT_REF);
133 		goto done;
134 	}
135 
136 	err = parse_ref_line(ref, name, line);
137 done:
138 	free(line);
139 	fclose(f);
140 	return err;
141 }
142 
143 static char *
144 get_refs_dir_path(struct got_repository *repo, const char *refname)
145 {
146 	if (strcmp(refname, GOT_REF_HEAD) == 0 ||
147 	    strcmp(refname, GOT_REF_ORIG_HEAD) == 0 ||
148 	    strcmp(refname, GOT_REF_MERGE_HEAD) == 0 ||
149 	    strcmp(refname, GOT_REF_FETCH_HEAD) == 0 ||
150 	    strncmp(refname, "refs/", 5) == 0)
151 		return got_repo_get_path_git_dir(repo);
152 
153 	return got_repo_get_path_refs(repo);
154 }
155 
156 const struct got_error *
157 got_ref_open(struct got_reference **ref, struct got_repository *repo,
158    const char *refname)
159 {
160 	const struct got_error *err = NULL;
161 	char *path_ref = NULL;
162 	char *normpath = NULL;
163 	char *path_refs = get_refs_dir_path(repo, refname);
164 
165 	if (path_refs == NULL) {
166 		err = got_error_from_errno();
167 		goto done;
168 	}
169 	
170 	/* XXX For now, this assumes that refs exist in the filesystem. */
171 
172 	if (asprintf(&path_ref, "%s/%s", path_refs, refname) == -1) {
173 		err = got_error_from_errno();
174 		goto done;
175 	}
176 
177 	normpath = got_path_normalize(path_ref);
178 	if (normpath == NULL) {
179 		err = got_error(GOT_ERR_NOT_REF);
180 		goto done;
181 	}
182 
183 	err = parse_ref_file(ref, refname, normpath);
184 done:
185 	free(normpath);
186 	free(path_ref);
187 	free(path_refs);
188 	return err;
189 }
190 
191 void
192 got_ref_close(struct got_reference *ref)
193 {
194 	if (ref->flags & GOT_REF_IS_SYMBOLIC)
195 		free(ref->ref.symref.name);
196 	else
197 		free(ref->ref.ref.name);
198 	free(ref);
199 }
200 
201 struct got_reference *
202 got_ref_dup(struct got_reference *ref)
203 {
204 	struct got_reference *ret;
205 
206 	ret = calloc(1, sizeof(*ret));
207 	if (ret == NULL)
208 		return NULL;
209 
210 	ret->flags = ref->flags;
211 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
212 		ret->ref.symref.name = strdup(ref->ref.symref.name);
213 		if (ret->ref.symref.name == NULL) {
214 			free(ret);
215 			return NULL;
216 		}
217 		ret->ref.symref.ref = strdup(ref->ref.symref.ref);
218 		if (ret->ref.symref.ref == NULL) {
219 			free(ret->ref.symref.name);
220 			free(ret);
221 			return NULL;
222 		}
223 	} else {
224 		ref->ref.ref.name = strdup(ref->ref.ref.name);
225 		if (ref->ref.ref.name == NULL) {
226 			free(ret);
227 			return NULL;
228 		}
229 		memcpy(ret->ref.ref.sha1, ref->ref.ref.sha1,
230 		    SHA1_DIGEST_LENGTH);
231 	}
232 
233 	return ret;
234 }
235 
236 static const struct got_error *
237 resolve_symbolic_ref(struct got_reference **resolved,
238     struct got_repository *repo, struct got_reference *ref)
239 {
240 	struct got_reference *nextref;
241 	const struct got_error *err;
242 
243 	err = got_ref_open(&nextref, repo, ref->ref.symref.ref);
244 	if (err)
245 		return err;
246 
247 	if (nextref->flags & GOT_REF_IS_SYMBOLIC)
248 		err = resolve_symbolic_ref(resolved, repo, nextref);
249 	else
250 		*resolved = got_ref_dup(nextref);
251 
252 	got_ref_close(nextref);
253 	return err;
254 }
255 
256 const struct got_error *
257 got_ref_resolve(struct got_object_id **id, struct got_repository *repo,
258     struct got_reference *ref)
259 {
260 	const struct got_error *err;
261 
262 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
263 		struct got_reference *resolved = NULL;
264 		err = resolve_symbolic_ref(&resolved, repo, ref);
265 		if (err == NULL)
266 			err = got_ref_resolve(id, repo, resolved);
267 		free(resolved);
268 		return err;
269 	}
270 
271 	*id = calloc(1, sizeof(**id));
272 	if (*id == NULL)
273 		return got_error_from_errno();
274 	memcpy((*id)->sha1, ref->ref.ref.sha1, SHA1_DIGEST_LENGTH);
275 	return NULL;
276 }
277 
278 char *
279 got_ref_to_str(struct got_reference *ref)
280 {
281 	char *str;
282 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
283 		if (asprintf(&str, "ref: %s", ref->ref.symref.ref) == -1)
284 			return NULL;
285 	} else {
286 		str = calloc(1, SHA1_DIGEST_STRING_LENGTH);
287 		if (str == NULL)
288 			return NULL;
289 		str = got_sha1_digest_to_str(ref->ref.ref.sha1, str,
290 		    SHA1_DIGEST_STRING_LENGTH);
291 	}
292 
293 	return str;
294 }